Facultyhttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/4552015-01-24T17:51:06Z2015-01-24T17:51:06ZComposition Dependent Study of AC conductivity in AsSe samplesMadhusoodanan, K NNisha, Rhttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/46492014-08-20T20:30:22Z2014-05-01T00:00:00ZComposition Dependent Study of AC conductivity in AsSe samples
Madhusoodanan, K N; Nisha, R
The room temperature AC conductivity σ(ω) of amorphous AsSe samples with various compositions have been measured in the 103 -106 Hz frequency range. The results indicate that ac conductivity is proportional to n with n=0.89±.01 in the 103 –106 Hz frequency range. Consideration of different models for the frequency –dependent conductivity leads to thermally activated hopping as the most likely process
International Journal of Scientific and Research Publications, Volume 4, Issue 5, May 2014
2014-05-01T00:00:00ZThermal Properties of Polytetrafluoroethylene/ Sr2Ce2Ti5O16 Polymer/Ceramic CompositesJacob, PhilipSubodh, GManjusha, M VSebastian,M Thttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/20302014-07-11T05:49:36Z2008-01-01T00:00:00ZThermal Properties of Polytetrafluoroethylene/ Sr2Ce2Ti5O16 Polymer/Ceramic Composites
Jacob, Philip; Subodh, G; Manjusha, M V; Sebastian,M T
Polytetrafluoroethylene (PTFE) composites
filled with Sr2Ce2Ti5O16 ceramic were prepared by a powder
processing technique. The structures and microstructures
of the composites were investigated by X-ray diffraction
and scanning electron microscopy techniques. Differential
scanning calorimetry showed that the ceramic filler
had no effect on the melting point of the PTFE. The effect
of the Sr2Ce2Ti5O16 ceramic content [0–0.6 volume fraction
(vf)] on the thermal conductivity, coefficient of thermal
expansion (CTE), specific heat capacity, and thermal diffusivity
were investigated. As the vf of the Sr2Ce2Ti5O16 ceramic increased, the thermal conductivity of the specimen
increased, and the CTE decreased. The thermal conductivity
and thermal expansion of the PTFE/Sr2Ce2Ti5O16
composites were improved to 1.7 W m21 8C21 and 34
ppm/8C, respectively for 0.6 vf of the ceramics. The experimental
thermal conductivity and CTE were compared
with different theoretical models.
2008-01-01T00:00:00ZYoung’s modulus of silicon nitride used in scanning force microscope cantileversJacob, PhilipKhan, AHess, Phttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/20292010-12-14T20:31:45Z2004-02-15T00:00:00ZYoung’s modulus of silicon nitride used in scanning force microscope cantilevers
Jacob, Philip; Khan, A; Hess, P
The Young’s modulus and Poisson’s ratio of high-quality silicon nitride films with 800 nm thickness,
grown on silicon substrates by low-pressure chemical vapor deposition, were determined by
measuring the dispersion of laser-induced surface acoustic waves. The Young’s modulus was also
measured by mechanical tuning of commercially available silicon nitride cantilevers, manufactured
from the same material, using the tapping mode of a scanning force microscope. For this
experiment, an expression for the oscillation frequencies of two-media beam systems is derived.
Both methods yield a Young’s modulus of 280–290 GPa for amorphous silicon nitride, which is
substantially higher than previously reported (E5146 GPa). For Poisson’s ratio, a value of n
50.20 was obtained. These values are relevant for the determination of the spring constant of the
cantilever and the effective tip–sample stiffness
2004-02-15T00:00:00ZUltrasonic measurement of the elastic properties of benzoyl glycine single crystalsJacob, PhilipAlex,A Vhttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/20282014-07-09T05:17:07Z2004-01-01T00:00:00ZUltrasonic measurement of the elastic properties of benzoyl glycine single crystals
Jacob, Philip; Alex,A V
Certain organic crystals are found to possess high non- linear optical coefficients,often one to two orders of magnitude higher than those of the well known inorganic non-linear optical materials.Benzoyl glycine is one such crystal whose optical second-harmonic generation efficiency is much higher than that of potassium dihydrogen phosphate. Single crystals of benzoyl glycine are grown by solvent evaporation technique using N,N-dimethyl formamide as the solvent.All the nine second-order elastic stiffness constants of this orthorhombic crystal are determined from ultrasonic wave velocity measurements employing the pulse echo overlap technique.The anisotropy of elastic wave propagation in this crystal is demonstrated by plotting the phase velocity, slowness,Young's modulus and linear compressibility surfaces along symmetry planes.The volume compressibility, bulk modulus and relevant Poisson's ratios are also determined. Variation of the diagonal elastic stiffness constants with temperature over a limited range are measured and reported.
2004-01-01T00:00:00Z